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Measures of Central Tendency

Measures of Central Tendency section 9.1 The mean of a set of numbers is the average. Example:12, 5, 7, 16 mean = ( )/4 = 10

Measures of Central Tendency section 9.1 Example:The mean of five test scores is 81. What is the sum of the test scores?

Measures of Central Tendency section 9.1 page 368 #37

Measures of Central Tendency section 9.1 The median of a set of numbers is the middle number. Example:5, 3, 11, 9, 8, 15, 2 Order the numbers: 2,3,5,8,9,11,15 The median is the middle number = 8

Measures of Central Tendency section 9.1 If there are an even number of values: Example:5, 3, 11, 9, 8, 15, 2, 20 Order the numbers: 2,3,5,8,9,11,15, 20 The median is the average of the middle numbers = (8+9)/2 = 8.5

Measures of Central Tendency section 9.1 Mode = most frequently occurring value (may have more than one mode) ex: 1,1,2,2,2,5,7,8,8,8,9 Midrange = (low val + high val) / 2

Measures of Central Tendency section 9.1 Values: Median = "50th percentile" = Q2 First Quartile = median of lower half = Q1 Third Quartile = median of upper half = Q3

Measures of Central Tendency section 9.1 Values: What are Q 1, Q 2 and Q 3 ?

Measures of Central Tendency section 9.1 Page 368 #51

Measures of Dispersion

Measures of Dispersion section 9.2 Two data sets with mean = 50 Data Set 1:48, 49, 50, 51, 52 Data Set 2:10, 20, 50, 80, 90 What is the difference?

Measures of Dispersion section 9.2 Range = high val - low val Example:11, 9, 6, 12, 17 What is the range?

Measures of Dispersion section 9.2 Standard Deviation: "average" deviation from the mean Data Set:2, 3, 5, 8, 9, 11, 18

The Normal Curve

The Normal Curve section 9.3 Data which approximates a Normal Distribution

The Normal Curve section 9.3

Use table 9.4 to find the area to the right of z = 1.34

The Normal Curve section 9.3 Use table 9.4 to find the area to the left of z = 1.62

The Normal Curve section 9.3 Use table 9.4 to find the area between z = and z = -1.64

The Normal Curve section 9.3 Page 394 #49

The Normal Curve section 9.3 Page 394 #50

The Normal Curve section 9.3 Assume that math SAT scores are normally distributed with a mean of 500 and a standard deviation of 100. What percent of students who took the test have a math score below 550?

The Normal Curve section 9.3 Assume that math SAT scores are normally distributed with a mean of 500 and a standard deviation of 100. What percent of students who took the test have a math score above 650?

The Normal Curve section 9.3 Assume that math SAT scores are normally distributed with a mean of 500 and a standard deviation of 100. What percent of students who took the test have a math score between 550 and 650?

Linear Regression